what might be an easy way to guesstimate a smoothing stub for a Karlson coupler?

[freddi]

the front cavity peak and reflections can be reduced - nulled with a damped stub attached or part of the front cavity's top. Hornresp might be able to estimate. Empirical testing could sort the typical areas of peaking with regards to front chamber aspect and height.

There was some discussion at MMJ's "Transflex" thread.

I'd like to employ it in a simple midrange BP4 module.

The 3 way stack "sounds pretty good" as is - - or I would not mucK...

 

[xrk971]

You can calculate the 1/4 wave stub with speed of sound. I usually make it at least 1in height by width of cabinet and depth needed for the frequency. Stuff with fiberglass/polyfill etc.

Calculation for example if you have 470Hz peak you need to smooth over. Take 342 m/s sound speed and divide by 470Hz and you get 0.73m and divide by 4 for quarter wave and you get 18.1cm or 7.2in long stub. So make a channel 1in high x 7.2in deep x cabinet internal width. Stuff with fiberglass progressively denser at the closed end and fluffier near the opening. If not enough attenuation, increase height (1.5in or etc).

 

[freddi]

It was suggested by MMJ back in 2019 that Hornresp could model a Karlson with damping stub. Without a test = ?

 

[freddi]

for a woofer module this little box designed by TB46 for my B&C 15PZB40 could work - it would not have quite the "hit" of a regular Karlson alignment
but have adequate output power and a nice height to hold the midrange K-coupler and K-tube tweeter units